The background of the present invention may be summarized in one word: “wires”. Most stored program controlled systems of even minor complexity consist of a plurality of single or limited functionality processing units, each of which is connected to one or more of the other processing units by wires. There are literally millions of miles of interconnecting wires in current use in systems as diverse as stored program controlled telephone and data switching systems, robotic assembly lines, high speed mainframe computers, modern aircraft, local area networks, etc.
These wires provide the medium for communication signals among processing units to facilitate functionality of the whole. For example, a signal generated by a processing unit in the cockpit of an airplane is transmitted over a wire to a processing unit in the tail section to manipulate the tail control surfaces. Likewise, in a stored program controlled telephone switching office, a signal to connect a telephone call from one line to another is carried by wires interconnecting the processing units to which the telephone lines are connected.
In most stored program control systems, the “interconnecting wires” is a complex array of backplane wiring interconnecting processing units on cards, shelves of cards and cabinets of shelves. Each of these (card, shelf of cards, cabinet of shelves) may be considered a “processing unit”, because cards and shelves of related tasks are usually wired together in functional units, and then generally wired together in a cabinet. Cabinets of large stored program controlled systems are interconnected by bundles of wires (cables). Thus, the interconnecting wires provide communications paths that enable the individual processing units of the stored program controlled system to interact, thus providing the functionality of the whole.
A single change in an individual processing unit of a stored program controlled system may cause literally thousands of interconnecting wires to be moved from one processing unit to another, or connected or reconnected in some fashion. These new connections must be carefully planned and executed by skilled craftspeople that make each connection and then test it. One minor error may cause a major malfunction.
Therefore, a problem in the art is interconnecting processing units in a stored program controlled processing system with extensive wiring which is difficult to install, maintain and modify.